The present invention relates to a knuckle and hub lock for a vehicle axle, particularly a knuckle and hub lock actuator assembly that are formed in an integral fashion. The hub lock actuator assembly actuates a clutch shiftable between positions for connecting and disconnecting drive and driven components of the vehicle to render selected wheels passive or power-driven. The invention finds application in axle assemblies which selectively receive drive torque.
Some four-wheel vehicles are capable of being selectively switched from a condition of two-wheel drive (often referred to as xe2x80x9c4xc3x972xe2x80x9d) to a condition of four-wheel drive (often referred to as xe2x80x9c4xc3x974xe2x80x9d). Such a vehicle requires that one of the axles comprise a set of half shafts in which a hub is locked to the half shaft and receiving drive torque part of the time, but the hub may be rotationally disengaged from the half shaft at other times, during which the hubs are able to freewheel. This is desirable as it prevents forced rotation of the drive train as a result of the front wheels being driven as the vehicle is propelled.
In a vehicle having two axles with four wheels, only one of the axles will be provided with steerable wheels. This axle is usually the axle which receives drive torque on a selective basis, the non-steerable axle normally being provided with full-time drive torque. While the technical requirements for a non-steerable, full-time-drive axle are among the least complex of the possible configurations, the combination of steerability in a selective drive axle provides the greatest amount of technical challenge. For that reason, among others, it is highly desirable to be able to combine and simplify structures to the fullest extent possible.
There are several devices shown in the prior art disclosing mechanisms for rotationally engaging and disengaging a hub. Many of these devices disclose locking hub clutch systems that have a separate vacuum or pressure chamber located at the outer end of the wheel hub. The problem with these devices is that they must be attached or integrated into areas where there is little room. This may result in many other problems, such as unsightly protrusions extending from the center of the wheel. One prior art device discloses a hub locking clutch device in which the locking actuator piston operates in a machined cylinder within the axle stub shaft and the axle joint yoke. In this device the cylinder and the locking actuator piston are an integral part of the axle shaft. While this device does not require attachment of a separate vacuum or pressure chamber, like the wheel end devices, the space available in the axle provides a relatively small diameter available for transmitting torque between its elements, resulting in higher stresses on its members.
In yet another device, the hub locking actuator is a hydraulically actuated ring and diaphragm which is attached to the knuckle. While this device has a much larger diameter available for transferring torque than the previous devices, it still requires the addition of a separate pressure chamber.
It is therefore an advantage of the present invention to provide a simplified version of a hub locking actuator device which is formed as an integral part of the knuckle.
This advantage of the present invention is achieved by an integrated wheel end assembly for a vehicle comprising a knuckle coupled to the vehicle and integrally housing a hub lock actuator assembly, a bearing assembly mounted to the knuckle, a cylindrical wheel hub mounted on the bearing assembly, a stub shaft, and a clutch member, wherein the hub lock actuator assembly moves the clutch member selectively between a first non-driving position and a second driving position. The assembly receives drive torque from a half shaft through a constant velocity joint. The bearing assembly allows for relatively free rotation of the wheel hub about a central axis thereof. The wheel hub has a flange for mounting the wheel at an outboard end thereof and a drive flange at an inboard end thereof. An outer circumference of the drive flange has a plurality of external teeth spaced evenly therearound. An outboard end of the stub shaft is rotatingly supported in the wheel hub and an inboard end thereof defines a housing for the CV joint. This housing has a plurality of external teeth identical in size and number to the teeth on the drive flange and the housing and flange are positioned axially adjacent to each other. The clutch member has internal teeth sized and adapted for engaging the external teeth on the housing and the drive flange and is slidable axially between a first position in which the clutch member teeth engage only the CV housing teeth and no drive torque is transferred from the half shaft to the wheel hub and a second position in which the clutch teeth engage both the CV housing teeth and the drive flange teeth and drive torque is transferred from the half shaft to the wheel hub through the engagement. A biaser is provided to bias the clutch member to a 4xc3x972 mode fail safe position by biasing the clutch member in the inboard direction.